1. Field of the Invention
This invention relates to a compressor and especially for a compressor for use in a cooling system.
2. Description of the Related Art
A conventional cooling system for an automobile is shown in FIG. 6. As shown in FIG. 6, the cooling system has an expansion valve 1, an evaporator 2, a compressor 3 and a condenser 4. A coolant is expanded by the expansion valve 1 and is changed into a low temperature gas. A gas coolant is sent to the evaporator 2 which is mounted in the interior of the automobile. The evaporator 2 absorbs heat from the interior air. The absorbed heat is transferred to the gas coolant while the coolant maintains its gaseous state. This arrangement lowers interior temperature. The heated gas coolant is transmitted to the compressor 3 and is compressed into a pressurized high temperature gas. The pressurized high temperature gas then flows to the condenser 4. The pressurized high temperature gas transfers heat to the condenser 4 and is changed into a low temperature liquid coolant. The foregoing cycle is continued in order to maintain room temperature constant.
A conventional compressor has a piston which is movable in response to a rotating slant plate or has an eccentric rotor in order to change a heated gas coolant into a heated high pressure gas coolant. For example, Japanese Patent Laid-Open 57 (1982) - 41493 shows a vane-type compressor. This compressor has an eccentric rotor in a cylinder. The rotor rotates eccentrically in contact with the cylinder wall. The vane is provided at the cylinder and extends to the rotor. A working space is provided by the rotor, the vane and the cylinder. The rotation of the rotor changes the volume of the working space and compresses a coolant gas. This type of compressor is powered by the output of an engine, however, it is not energy efficient and engine power output loss in driving the compressor is large. If rapid cooling is needed, a conventional system reduces the amount of air flow through the condenser in order to decrease the load. Therefore, it takes time to lower the temperature. Further, the compressor works constantly even after the temperature reaches the set temperature. As such, energy consumption is increased and engine output energy is wasted. Because the vane arrangement is provided at the cylinder, the size of the compressor may be too large to mount in an automobile due to small space availability. Additionally, when the rotational speed of the rotor is high, movement of the vane is also increased. A force of inertia effects the contacts between the vane and the rotor. The vane has to be pressed to the rotor by a strong spring against the force of inertia. Due to this pressing contact, the rotor is worn by the contact of the vane.